This is a very large, 3.9" long, single cactus amethyst point mined in the Magaliesberg Mountains of South Africa. This is one of the larger single points that I've seen and it has great color and a nice termination. The base has been cut flat so that it stands up nicely on a hard surface.
Cactus quartz, often also referred to as spirit quartz, is a variety of quartz characterized by second-generation druzy crystals growing on the faces of larger quartz crystals. The small second-generation crystals point away from the prism and their orientation is not related to the crystallographic orientation of the central crystal. Cactus quartz is currently only known from the Magaliesberg Mountains region of South Africa, and comes in a variety of shades ranging from white to deep purple to orange colorations. The deep purple amethyst points are the rarest and most coveted by collectors.